Conventionally a belt conveyor comprises an elongate belt arranged as an endless loop supported at its ends by opposite roller assemblies, one of which may be driven. The belt defines upper and lower runs and is carried by a generally rigid supporting frame. The supporting frame consists generally of an elongate belt platform carrying the roller assemblies supporting the belt and a platform support structure usually in the form of a leg assembly supporting the belt platform in an elevated position relative to floor level.
In a conventional conveyor the frame of the conveyor is fabricated from a large plurality of separately formed components, by bolting or welding the components together. In many conveyor applications a fabricated frame is undesirable as the points of interconnection of components tend to become sites of corrosion in use. Moreover, in applications such as food processing, a conveyor frame fabricated from a plurality of individual components presents serious hygiene problems. The crevices defined where components are bolted together act as traps retaining food materials spilled from the conveyor (food spoil) and thus constitute sites for bacterial growth. By their nature such crevices are extremely difficult to clean and thus the cleanliness, and freedom from bacterial contamination, which is a prerequisite of the food industry, is difficult to maintain.
The use of welding, rather than bolted joints between components of the frame eliminates some of the crevices, but does not eliminate the hygiene problem. It is found that welding together of the components, particularly where the components are formed from stainless steel, causes changes in the internal structure of the metal in the region of the weld which allows bacteria to penetrate the material at the grain boundaries of the material adjacent the weld resulting in bacterial colonisation of the material, leading to corrosion and the formation of crevices which can trap food spoil leading to further bacterial growth.
In consequence existing conveyors need to be cleaned frequently, using steam cleaning apparatus, caustic solvents, and significant amounts of manual labour, in order to preserve the hygiene standards necessary in the food industry.
It is an object of the present invention to provide a conveyor, suitable for use in the food industry, which facilitates the maintenance of the necessary hygiene standards with a lower frequency, or less intense, cleaning regime than is currently necessary.